Bicycle gearing, computed

One page per calculation. Every figure is derived from a relation we state, so you can check it rather than trust it.

• Gain ratio calculator — Work out gain ratio from your chainring, cog, tyre and crank length — the one gearing number that accounts for the lever you actually push.
• Gear inches calculator — Work out gear inches from your chainring, cog and tyre — derived from ETRTO geometry, not copied from a rollout table.
• Gear table and gear range calculator — Build the full table of gear inches for every chainring and cog combination on your bike, with the total gear range and the combinations that duplicate each other.
• Speed at cadence calculator — Work out your road speed from a gear and a pedalling cadence, with development — the distance one turn of the cranks covers — shown alongside.